断路器操作回路的智能化监测系统设计

为了监测断路器操作回路中跳/合闸回路、压板和保护出口接点的状态,并对其薄弱环节故障进行预警以避免断路器误动或拒动,设计了断路器操作回路的智能化监测系统。该系统改进了现有跳/合闸回路,并给出了系统中元件的选型与参数整定依据,能够实现跳/合闸回路的全工况监视和保护。为了实时监测断路器操作回路压板和保护出口接点的状态,实现压板误操作和保护出口接点故障报警,该系统采取了配合使用电感式接近开关和霍尔电压传感器的方法,并给出了传感器的具体安装位置。该系统采用单片机处理并上传传感器采集的现场信息,利用LabVIEW编写后台软件界面,能够实现实时状态显示、人机交互、历史数据存储和故障报警等功能。     

Unidirectional Wetting in the Hydrophobic Wenzel Regime

Unidirectional wetting surfaces can cause liquid droplets to flow/move in one direction while pinning them in the other directions, a feature that is useful for biosensing, adhesives, thermal management, and microfluidics. Such surfaces can be fabricated by employing structurally or chemically asymmetric nanostructures. While unidirectional wetting in the hydrophobic Wenzel regime had previously been observed on surfaces decorated with chemically asymmetric nanostructures, it has yet to be demonstrated on structurally asymmetric nanostructures. Based on the current understanding of the phenomenon, this can only be achieved using highly bent nanowires. Here, evidence to the contrary is provided by showing that mildly bent nanowires can also bring about unidirectional wetting in the hydrophobic Wenzel regime, even for contact angles beyond the superhydrophobic limit. Using NaCl precipitation, the unidirectional wetting mechanism is analyzed on a nanoscale level and it is found that the criteria for unidirectional wetting to take place in the hydrophobic Wenzel regime are different from that in the hydrophilic Wenzel regime. Moreover, it is revealed that slight wetting in the pinned direction can be caused by large scale deformation of high aspect ratio nanostructures during droplet spreading, which may be part of the reason behind previous observations of near‐unidirectional wetting on bent nanowires with high aspect ratios.     

Tailored Porphyrin Assembly at the Oil–Aqueous Interface Based on the Receding of Three‐Phase Contact Line of Droplet Template

A novel and robust approach to controllable porphyrin assembly is developed at the oil–aqueous interface by tuning the receding of three‐phase contact line of droplet template. The assembled morphologies (ring–, wheel–, and hole–shell shape), aggregate modes and crystal states of porphyrin molecules can be effectively tailored by modulating the receding behavior of three‐phase contact line, which can be realized by varying the hysteresis behavior of substrate or solvent ratios. The developed method for tailored porphyrin assembly will offer an important insight for the design and creation of novel structures.     

液压支架立柱组合蕾形密封圈结构参数与密封性能研究

以某大采高液压支架立柱组合蕾形密封圈为研究对象,采用有限元法分析唇内、外倾角和唇谷高等结构参数对组合蕾形密封圈静密封性能的影响,同时研究油压压力、密封间隙、立柱活塞速度、摩擦因数对密封圈动密封性能的影响。结果表明:一定取值范围内,唇内、外倾角和唇谷高越大,静密封性能越好;油压越大、密封间隙越小,动密封性能越好;摩擦因数越大,外行程时动密封性能越好,内行程时则相反;活塞运动速度对动密封性能影响较小。为保证该组合蕾形密封圈具有良好的综合密封性能,各参数优化取值范围为:唇外倾角20°~30°,唇内倾角20°~35°,唇谷高度12.2~13.2 mm,摩擦因数小于等于0.1,密封间隙0.1~0.3 mm,油压不超过50 MPa。     

考虑硬度变化的结合面法向接触刚度分形模型*

基于分形几何理论,考虑微凸体因应变硬化而造成弹塑性变形阶段硬度随变形量变化而变化,建立结合面第一、第二弹塑性变形阶段单次加载刚度分形模型。推导出在计入硬度变化的情况下,单个微凸体在弹塑性变形阶段法向接触刚度与接触面积之间的关系式,进而得出结合面在弹塑性变形阶段法向接触刚度与接触面积、接触载荷之间量纲为一的关系式,并通过仿真分析得出相关参数对结合面法向接触刚度的影响。仿真结果显示:考虑硬度变化时,结合面量纲一法向接触刚度的值与法向实际接触载荷、实际接触面积之间存在关系;结合面法向接触刚度随着分形维数D的增大而增大;分形维数一定时,结合面法向接触刚度随表面长度尺度参数G值增大而增大。     

武汉里分公共空间与外部城市公共空间利用联系探究——以法租界内海寿里和昌年里为例

里分住区是武汉最具代表性的传统民居建筑形式。今天,随着城市社会的高速发展,里分这一历史建筑形式正在受到严重的冲击。住区环境的恶化使之在城市环境中愈发的衰败,它们或被拆建或者在城市中被孤立起来。该文以武汉法租界为研究对象,分别选取海寿里、昌年里及其附近的城市公共空间进行分析探究并提出改造意见,旨在解决里分自身问题的同时,更加强里分与里分、里分与城市公共空间的辐射联系。     

Application of response surface methodology for modeling and optimization of membrane distillation desalination process

In this work, response surface methodology (RSM) was applied for modeling and optimization of operating parameters for water desalination by direct contact membrane distillation (DCMD) process using polypropylene membrane (PP) with low pore size. Operating parameters including vapor pressure difference, feed flow rate, permeate flow rate and feed ionic strength were selected and the optimum parameters were determined for DCMD permeate flux. The developed model for permeate flux response was statistically validated by analysis of variance (ANOVA) which showed a high value coefficient of determination value (R² = 0.989). The obtained optimum operating parameters were found to be 0.355 × 10⁵ Pa of vapor pressure difference, feed flow rate of 73.6 L/h, and permeate flow rate of 17.1 L/h and feed ionic strength of 309 mM. Under these conditions, the permeate flux was 4.191 L/(m² h). Compared to a predicted value, the deviation was 3.9%, which confirms the validity of the model for the DCMD process desalination optimization. In terms of product water quality, the DCMD process using hydrophobic PP membrane can produce high quality of water with low electrical conductivity for all experimental runs.     

模拟宫腔液对加成型液体硅橡胶性能的影响

采用模拟宫腔液对加成型液体硅橡胶硫化胶进行浸泡处理,通过全反射傅里叶红外光谱分析、表面接触角和热重分析对模拟宫腔液浸泡前后的硫化胶进行表征,研究模拟宫腔液的浓度和浸泡时间对硫化胶性能的影响。结果表明,随着浸泡时间的延长和模拟宫腔液浓度的增大,硫化胶的拉伸强度、断裂伸长率和撕裂强度有所下降,硬度基本不变;但即使经过3倍标准浓度模拟宫腔液90℃下浸泡12天后,硫化胶的拉伸强度、断裂伸长率、撕裂强度的降低幅度均低于10％,而且硫化胶的化学性质稳定,亲水性提高,热稳定性良好。因此,加成型液体硅橡胶是制作宫内节育器的理想材料。     

原油中酸性组分对油/水乳状液的影响研究

原油中的酸性组分是天然表面活性物质,影响油/水乳状液的稳定性,相关研究对采出液破乳有重要参考价值。作者研究了原油中酸性组分对油/水乳状液破乳效果、乳状液粘度、油/水接触角、界面膜强度的影响,结果如下:随w(酸性组分)从2.25%增加到2.65%,85℃时,脱水率由81.2%降低至14%,粘度由212.3mPa·s增加到1 452mPa·s,乳状液的稳定性大幅度增加;随w(酸性组分)增加,油/水接触角减小,界面膜强度增加;虽然间隔都是0.2%,w(酸性组分)为2.25%和2.45%时,油/水接触角、单滴破裂率相差较大,但w(酸性组分)为2.45%和2.65%时相差较小。     

气承式充气膜结构风载下的索膜接触分析

柔性的膜结构具有较强的几何非线性,在荷载作用下将发生大位移变形,索和膜之间的相对滑动不可避免。考虑风荷载、风向、风速、内压及摩擦系数的改变,运用通用有限元程序ANSYS,对气承式充气膜结构的索与膜面进行接触分析,并计算自重影响。结果分析表明:索可以等效为边界约束的增加,使得结构刚度增大,增强了结构的整体稳定性,有效预防膜面掀开、膜材撕裂等破坏;迎风面索对结构抵抗外荷载没有突出功效;合理的内压可以有效维持结构形态、抵抗外荷载;不同摩擦系数对索轴力及接触分析的影响不容忽略。